This invention relates generally to inductively operating sensors and particularly relates to such a sensor for measuring a ferromagnetic work piece.
Such inductive sensors are utilized for the nondestructive testing of work pieces for quality control; particularly they are used for testing technologic properties such, for example, as the hardness, hardening and heat treatment of work pieces. The known sensors of the type described, however, all have the drawback that it is hardly possible to obtain exactly reproducible measuring results. There are too many influences which are hard to control and which result in a broad spread of the measuring results. Accordingly, these do not have great reliability. By way of example, it has been found that the relative position between the measuring head and the work piece during the measurements is of decisive importance for the measuring results. It is this fact which makes it practically impossible to obtain measuring values which are easily reproducible with the known sensors having spherical or ball-shaped measuring heads.
It is accordingly an object of the present invention to improve a sensor of the type described so that it is possible to obtain reliable measuring results which therefore have a higher degree of reliability and which are reproducible without difficulty.